Mission Aircrew Course Electronic Search Patterns (APR 2010)

Mission Aircrew Course Electronic Search Patterns (APR 2010)

Aircrew Tasks O-2005 OPERATE THE AIRCRAFT DIRECTION FINDER (P)
O-2006 PERFORM ELT SEARCHES (P) O-2007 LOCATE AND SILENCE AN ELT ON THE GROUND (P) O-2101 DESCRIBE HOW ELTS ARE DETECTED (P) O-2108 ASSIST IN ELT SEARCHES (O)

Objectives Response during initial phase, including signal fade
Discuss the various types of ELTs. Describe how an ELT can be detected. Describe how the aircraft DF works in both the Alarm and DF modes. Discuss using the DF during a typical ELT search Response during initial phase, including signal fade Response when getting close Response as you pass over the beacon

Objectives Describe the following ELT search methods: Homing Wing null
Aural Signal Discuss signal reflection and interference. Describe how to silence an ELT and the legal issues involved.

Objective: The Elusive ELT
Automatic radio beacon (100 milliwatts) Roughly equal to that of a regular flashlight Can be heard on a line-of-sight basis. Remember that the ELT may be attached to an aircraft or vessel in distress! Click Icon to Hear an ELT ©2000 Scott E. Lanis 6

The ELT Activated by g-force (when armed)
Some can be activated by the pilot in the cockpit Three frequencies: 121.5 MHz (VHF emergency) 243 MHz (UHF emergency – military guard) 406 MHz (third generation advanced ELT/EPIRB/PLB) General types: General aviation aircraft Military (“beepers” or “beacons”) Marine EPIRB Personal Locator Beacons (PLBs) Advanced (406) Test station (training practice beacon) 10.1.1 Objective 10.1 – Discuss the various types of ELTs.

ELT Antenna

Most aircraft have ELTs installed
But they don’t always survive a crash Less than one-third of all crashes have a survivable (operable) ELT.

Military beacons Most common type is the URT-33/C
Personnel ejecting/parachuting will most likely have a MHz beacon Some downed pilots may be able to communicate via two-way radio on MHz using a PRC-90 military survival radio Beacon mode transmits like an ELT on 243 MHz You can monitor (and track!) this frequency on your aircraft’s DF unit

Personal beacons Personal Locator Beacon (PLB)
Sometimes “Personal Emergency Transmitter” (PET) Intended for hikers, hunters, boaters, and other remote wilderness travelers MOST Use a 406 MHz transmitter and a MHz homing signal (generally, at only 25 milliwatts) Many are also equipped with a built-in GPS receiver that provides lat/long coordinates Each PLB must be registered with NOAA

Marine EPIRB Emergency Position Indicating Radio Beacon
Similar to an ELT, an EPIRB is used on ships and boats Mandatory on certain commercial vessels Some activate automatically and others are manually activated By law, all must be 406 capable now Contact the marina operator.

Advanced ELTs Designed to operate with SARSAT/COSPAS
406 MHz beacons have data burst encoding that identifies each (registered) individual beacon Also produces a MHz homing signal and may transmit GPS coordinates Sends a coded signal that can be matched to a registration database The owner's name, address and type of aircraft is obtained from database, so AFRCC can call to see if the aircraft is really missing (70% resolved this way) Since geostationary satellites process the digital signal, it will be heard more quickly and allow a much faster response If the unit has a GPS receiver, it can transmit lat/long coordinates to further speed the search. The signal can also penetrate dense cover (e.g., trees). Still very expensive (~ three times as much as a MHz ELT Not mandatory in the United States; MAY become mandatory in Canada Still cost upwards of $1700, so don’t expect large-scale upgrades anytime soon.

Practice Beacon Training Beacons are registered as Test Stations, and referred to as “Practice Beacons” Includes ones used by CAP All practice beacons should operate on MHz (if it uses another frequency, don’t use it) During practice searches, avoid calling the practice beacon an ‘ELT’ when communicating over the radio May cause confusion Always use the term ‘Practice Beacon’ Its called a “Practice Beacon,” not an ELT.

Testing an Aircraft ELT
Can test the aircraft’s ELT within the first five minutes after each hour Only allowed up to three sweeps When was the last time you tested the ELT in your aircraft? Do you regularly monitor MHz after you land? Ensure your ELT didn’t activate This isn’t considered a test, by the way, but you can try this excuse if you like

Inadvertent Activation
Excessively hard landings (Welcome aboard, Ensign!) Inadvertent change of switch position During removal/installation Malfunction Non-ELT source on MHz (computers, broadcast stations, even pizza ovens!) Monsieur Murphy Check after landing. It’s very embarrassing to search for an ELT signal and find it in a CAP aircraft!

False Alarms At least 97%+ of received ELT signals are false alarms
Historically, for MHz ELTs about 1 in 1000 are actual emergencies For 406 MHz ELTs about 1 in 10 are actual emergencies They block emergency communications on and MHz (guarded by towers, ARTCC, and the military)

Initial ELT Detection Until 1 Feb 2009, most ELTs were initially detected by the SARSAT-COSPAS system This system no longer monitors and 243.0 SARSAT-COSPAS only listens for 406 MHz signals now Initial detection for an ELT must come from an airborne or surface-based asset Airliners, military aircraft, ATC facilities Participating civil traffic: YOU Using the Area of Intersection method should get you closer, you may need mission staff to assist

SARSAT Video

GOES 406 ELT Detection GEO Footprint LEO Footprint

QUESTIONS?

OK, So How Should I Treat an ELT Mission?
AS AN EMERGENCY! Its not possible to know whether an ELT signal is a distress signal or a false alarm Although the statistics are against it, you must act as though it is a distress call If you take advantage of it, every ELT mission allows you to keep your skills sharp!

Locating the ELT Signal
Route or parallel track to pick up the signal If no SARSAT hits or definitive LKP: 4,000 to 10,000 AGL Large track spacing (start at 60 nm, then do halves) Once signal is located, DF the signal 10.2 Objective 10.2 – Describe how an ELT can be detected.

Direction Finder (DF) A direction finder compares signal strengths from two antenna patterns to let the user know: When you are “centered” on a signal headed directly towards OR away from from the signal source Which direction to turn when not centered Similar to an ADF needle, but only points left or right, hence the term “left-right homing” 10.3.1 Objective 10.3 – Describe how the aircraft DF works in both the Alarm and DF modes.

L-Tronics DF Normal: Alarm toggle in ‘up’ position
DF: toggle is ‘down’

DF Antenna These are mounted on the bottom, but may be on top

Step 1: Acquire the Signal
To hear the signal you can use your L-Tronics receiver, the Becker DF, or one of the comm radios To acquire with a comm radio, turn the squelch OFF The static you hear may be annoying, but it will allow you to hear the signal at the earliest possible time Allows for a weak or distant signal to be heard Proceed at a reasonable altitude to the Intersection Area Or to the SARSAT hit (406 ELT) if you have one or to the point designated by your incident commander ©2000 Scott E. Lanis 29

Beginning The Search: Altitude Selection
Higher altitudes allow for reception of the ELT signal at greater distances ELTs transmit on MHz and MHz, both of which limit reception to “line of sight” Terrain will block ELT signals HIGHER is therefore usually BETTER to acquire a signal Medium altitude is generally better for searching (after signal heard) 3,000 to 5,000 AGL SIGNAL HEARD! NO SIGNAL NO SIGNAL ELT ©2000 Scott E. Lanis 30

Intersection Area

Step 2: Track (DF) the Signal
There are many different ways to DF an ELT signal: Left-Right DF Homing (L-Tronics DF) Wing Shadow Method Aural Search Metered Search Combinations of the above techniques 10.4 – 10.7 Objective 10.5 – Describe the following ELT search methods: homing, wing null (shadowing), aural search and signal search. ©2000 Scott E. Lanis 33

Wing Shadowing By flying the airplane in a circle, at some point the wing will block the ELT signal to the receiver antenna This causes an audible decrease in volume, called a “null” Almost any VHF-AM aircraft communications radio may be used with this method ©2000 Scott E. Lanis 34

Wing Shadowing: Antennas
To properly use the Wing Shadowing method, you MUST know where the antenna for the radio you are using is installed & located on the aircraft Communications radio antennas are usually, but not always, located above the wings Can be above the fuselage, in the tail, etc. L-Tronics Aircraft DF antennas may be above or below the aircraft Below the aircraft is the preferred installation ©2000 Scott E. Lanis 35

Communications Antennas Above the Wing
©2000 Scott E. Lanis 36

DF Antennas Below the Wing

QUESTIONS?

How To DF by Wing Shadowing (Also Called Wing-Null Method)
Fly a constant bank angle 360° turn the audio will “null,” or get significantly quieter, when your wing blocks the antenna’s reception of the ELT signal N S E W 45 135 225 315 10.5 – 10.7 Objective 10.5 – D ©2000 Scott E. Lanis 39

Wing Shadowing: Signal Blocking For Antennas Above the Wings
ELT NULL ©2000 Scott E. Lanis 40

Wing Shadowing: Antennas Above the Wing
Turn in a circle until you hear the null (significant decrease in volume) The ELT is 90º to your LEFT SUBTRACT 90º from your heading Or, keep it simple—use the 90º index N S E W 45 135 225 315 ELT ©2000 Scott E. Lanis 41

Wing Shadowing: Signal Blocking For Antennas Below the Wings
NULL NULL SIGNAL NULL ELT ©2000 Scott E. Lanis 42

Wing Shadowing: Antennas Below the Wing
Turn in a circle until you hear the null (significant decrease in volume) The ELT is 90º to your RIGHT: ADD 90º to your heading N S E W 45 135 225 315 ELT ©2000 Scott E. Lanis 43

Aural (Hearing) Search Method
This is based on the assumption that the area of equal beacon signal strength is circular: do NOT adjust volume during this search; you will need it to determine equal levels of signal Begin by plotting your position as soon as you receive the ELT signal Fly that course for a short distance, then turn 90º left or right and proceed until the signal fades Turn around (180º) and mark where the signal fades on the other side of the circle Plot chord lines similar to that of the diagram Bisect the chord lines at a perpendicular Plot a course to the location where the perpendicular lines intersect: this should be the location of the target! ©2000 Scott E. Lanis 44

Metered Search (Build & Fade) Method
This search requires a signal strength meter (like that on the L-Tronics DF units-if the DF portion of the unit is inoperative you can still use this type of search as long as RECeive is OK. Note your signal strength when beginning the search. Fly a straight line until the signal gets lower, then increases to your original level. Turn 180º and return to the lowest level of signal, then turn 90º left or right. You should now be headed directly towards or away from the transmitter. If the signal increases in strength, you are headed directly for the ELT. If the signal decreases in strength, turn 180º ©2000 Scott E. Lanis 46

Metered Search 3 ELT 2 6 4 5 MAXIMUM SIGNAL MAXIMUM THEN DROP SIGNAL 1
FADE MAXIMUM SIGNAL MAXIMUM SIGNAL THEN DROP FIRST SIGNAL 1 2 3 4 5 6 ELT 7 8 9 ©2000 Scott E. Lanis 47

Left-Right DF Homing Most CAP corporate aircraft have L-Tronics LA-Series Left-Right Homing DF units These units operate virtually the same, but there are two major varieties: Single Meter Models Dual Meter Models ©2000 Scott E. Lanis 48

L-Tronics DF Types Single Meter Model Dual Meter Model VHF-DF VHF DF
ALARM OFF m SENS ®VOL VHF-DF 243 121.6 AUX 121.5 DF REC L-Tronics ALARM OFF 243 121.6 AUX 121.5 m SENS ®VOL VHF DF DF STRENGTH ©2000 Scott E. Lanis 49

Frequency Switch Selects frequency to be used
Use MHz for actual ELTs/EPIRBs 243.0 MHz may also be used for all actual electronic searches Use MHz for training Refer to owners manual for use of the “AUX” position L-Tronics ALARM OFF m SENS ®VOL VHF-DF 243 121.6 AUX 121.5 DF REC ©2000 Scott E. Lanis 50

Mode Switch Only Single-meter units have this switch
Dual-meter units use two displays, so both REC and DF operate continuously and simultaneously REC is short for RECeive mode REC makes the unit’s dial work as a strength meter DF is short for Direction Find DF gives left-right homing to the ELT/EPIRB signal ALARM is for NON-MISSION flights only Use only during normal flying to alert the presence of an ELT or EPIRB L-Tronics ALARM OFF m SENS ®VOL VHF-DF 243 121.6 AUX 121.5 DF REC ©2000 Scott E. Lanis 51

Volume & Sensitivity Volume controls the audio level to the speaker or headsets Sensitivity controls the amount of signal that enters into the DF unit It is critical that the proper amount of signal enters the DF: half-scale, or the middle, is an optimum starting place As the signal gets stronger, reduce SENSITIVITY, not volume The DF will be unreliable when too much signal is received, so you must cut out part of it by reducing the sensitivity More than three-quarters scale is too much L-Tronics ALARM OFF 243 121.6 AUX 121.5 m SENS ®VOL VHF DF DF STRENGTH ©2000 Scott E. Lanis 52

DF SETTINGS FOR SINGLE METER MODELS
MISSIONS Select (or for training missions) Select DF Mode Turn Sensitivity to Maximum (Full Clockwise) Turn Volume to About Mid-Scale (comfortable level) DF Needle Will Move Slightly Left and Right NON-MISSION FLIGHTS Select 121.5 Select Alarm Mode Turn Sensitivity To Maximum Do not fly a mission in the alarm mode, it takes too long to activate ©2000 Scott E. Lanis 53

DF SETTINGS FOR DUAL METER MODELS
MISSIONS Select (or for training missions) Ensure Alarm Toggle OFF Turn Sensitivity to Maximum (Full Clockwise) Turn Volume to About Mid-Scale (comfortable level) DF Should Stay About Centered Strength Meter Will Move Up-Scale to Right NON-MISSION FLIGHTS Select 121.5 Turn Alarm Toggle On Turn Sensitivity To Maximum ©2000 Scott E. Lanis 54

PRE-FLIGHT FUNCTIONAL CHECK
Just as you pre-flight the rest of the aircraft, you should preflight your DF when going on an ELT electronic search mission These procedures are covered in the Mission Aircrew Reference Text and are summarized for premission reference in the Flight Guide. 10.3.1, Normal Operations and Checks ©2000 Scott E. Lanis 55

SIX STEPS Use these 6 steps for locating ELTs and EPIRBs with L-Tronics LA- series airborne DF equipment Use the full procedure every time for the best results RECeive HALF DF TURN CHECK SHOOT Each of these steps will be described in detail in the slides to follow 10.3.2 Objective 10.4 – Discuss using the DF during a typical ELT search. Include how the DF should respond during the initial phase (including signal fade), when you are getting close, and when you pass over the beacon. ©2000 Scott E. Lanis 56

Step 1: RECeive Once you have started to receive the ELT or EPIRB signal on the proper frequency If you have a single-meter unit, turn the mode selector to RECeive and turn the volume to a comfortable level If you have a dual meter unit, refer to the STRENGTH window (no need to change modes) ©2000 Scott E. Lanis 57

RECeive Mode/STRENGTH Window
In receive mode or in the strength window, the unit measures signal strength Needle to the left means low; to the right means high Values are relative depending on the sensitivity you have selected You may still be able to use the strength meter even if the DF is not functioning perfectly It is possible to locate an ELT using only the Receive Mode Utilize Aural Search/Metered Search methods to accomplish If the unit isn’t completely operable, try wing shadowing using one of the aircraft’s communications radios and use the DF unit’s strength meter as a backup using the aural/metered methods

Step 2: HALF Now that the unit is in RECeive mode and you have a good signal, turn the Sensitivity Knob to HALF SCALE This is in the center of the window If you are flying with a dual-meter unit, turn the Sensitivity Knob so the needle reads HALF SCALE in the STRENGTH window A half-scale strength reading will prevent too much signal (over sense) from entering the unit and will provide you with a good starting point It is also the optimum for the DF homing antennas ©2000 Scott E. Lanis 59

Step 3: DF For single-meter units, turn the mode selector knob to DF
In DF mode, you can think of the needle as always pointing Direct to Follow the target. For dual-meter models, simply refer to the DF window (no need to change modes) ©2000 Scott E. Lanis 60

A Direction Finding Primer: Antenna Theory
Antennas can be more or less directional depending on their design Imagine a car radio antenna: it is unidirectional Its pattern looks like the one on the left A Satellite Dish is highly directional It would have a pattern like the one on the right car radio antenna (monopole) satellite dish (parabolic reflector)

DF Antenna Antennas Below the Wing Antenna Elements
The aircraft DF unit has a 2 or 3 “element” antenna Commonly, we might call this two or three antennas It just means there are two or three rods! This antenna setup is directional One element actually receives the signal The other elements (rods) reflect the signal away from the first rod N98987 Antennas Below the Wing Antenna Elements

Antenna Reception Pattern
When viewed from the bottom, an antenna setup like the one pictured on the previous slide produces a reception pattern like the one shown here This pattern is called “carotid,” which means “heart-shaped” The pattern is the same even if the antennas are mounted above the wing Element 1 2 3 ©2000 Scott E. Lanis 63

DF Unit Antenna Pattern
REFLECTOR ELEMENTS TOP VIEW DIRECTIONAL ANTENNA PATTERN RECEIVING ELEMENT AIRCRAFT VIEW

Direction Finding Mode/Window
The DF mode rapidly alternates the receiving and reflecting antenna elements It chooses one element as the receiver and the other two as the reflectors, then switches to the other set This produces a carotid pattern each time the unit switches one is shown in blue, the other in yellow By comparing the two patterns, the unit will determine when they are equal When they’re equal, the needle centers! When the needle is centered, the target is either directly ahead or behind you!

Step 4: TURN Turn at least one FULL circle, noting where the DF needle centers Under good conditions, the needle will center twice When facing directly at the source of the signal When facing 180º away from the target You will solve this problem (called ambiguity) in the next step ©2000 Scott E. Lanis 66

WHEN THE PATTERNS ARE EQUAL, THE DF NEEDLE CENTERS!
DF CENTERS ELT (Possibility 1) Alternating Antenna Patterns WHEN THE PATTERNS ARE EQUAL, THE DF NEEDLE CENTERS! Alternating Antenna Patterns ELT (Possibility 2)

Step 5: CHECK Use a Turn to Tell
Remembering that in DF mode the needle always points Direct to Follow the target When you have the needle centered, turn left or right If you turn left and the needle goes left, the ELT is 180º from your present heading If you turn left and the needle turns right, the ELT is dead ahead ©2000 Scott E. Lanis 68

AMBIGUITY When Needle Centers ELT is Directly Ahead or Behind
ELT (Possibility 1) When Needle Centers ELT is Directly Ahead or Behind This situation is called “ambiguity” To Solve ambiguity: Use Turn to Tell Make a turn left or right The needle always pointsDirect to Follow the Target (DF!) ELT (Possibility 2)

DF NEEDLE ELT Compare the RED (LEFT) and the BLACK (RIGHT) antenna patterns In this case, the LEFT pattern is stronger than the RIGHT In DF mode, the needle would then point LEFT The needle always points Direct to Follow the Target!

SOLVING AMBIGUITY Actual ELT position is unknown to user
ELT (Possibility 1) ELT (Possibility 2) Actual ELT position is unknown to user Make a small turn left or right As a teaching reminder, “Use a TURN to TELL” SOLVING AMBIGUITY

ELT (Possibility 1) ELT (Possibility 2) Actual ELT position is unknown to user Make a small turn left or right As a teaching reminder, “Use a TURN to TELL” Example: TURN LEFT needle goes left SOLVING AMBIGUITY

Make a small turn left or right As a teaching reminder, “Use a TURN to TELL” Example: TURN LEFT If needle goes left ELT is to your left (behind you) SOLVING AMBIGUITY ELT (Possibility 2)

SOLVING AMBIGUITY If you turn Left and the needle moves Right
ELT (Possibility 1) ELT (Possibility 2) If you turn Left and the needle moves Right The ELT is in Front of you! SOLVING AMBIGUITY

SOLVING AMBIGUITY If you turn Left and the needle moves Right
ELT (Possibility 1) ELT (Possibility 2) If you turn Left and the needle moves Right The ELT is in Front of you! Example: Turn left Needle goes right SOLVING AMBIGUITY

SOLVING AMBIGUITY Solution:
ELT (Possibility 1) Solution: If you turn Left and the needle moves Right The ELT is in Front of you! SOLVING AMBIGUITY

N S E W 45 135 225 315 Step 6: SHOOT Use your DG to determine a bearing to the target & follow it You may need to fly through a zone of signal dropout Be watchful for signs of signal passage If you get signal passage, consider using the “pinpointing the target” techniques listed in this presentation Frequently repeat the FULL SIX STEPS to ensure you are heading in the right direction and that you didn’t inadvertently over fly the ELT ©2000 Scott E. Lanis 77

How A L-Tronics DF Unit Works: Summary
Two Main Modes of Operation RECeive DF RECeive Mode is a Strength Meter Left is low, right is high DF Mode Centers on Signal Always points to the signal Use a Turn to Tell when solving ambiguity Aircraft and ground units work the same way

QUESTIONS?

Reflections Reflections of an ELT signal work just like a flashlight off of a mirror Any flat, hard, or wet object can cause signal reflections Mountains, especially cliff faces Hangars and other metal structures Wet grass or ground Snow Large bodies of water or ice Power lines can also have a large effect on a low-powered signal such as an ELT 10.9 Objective 10.6 – Discuss signal reflection and interference. ©2000 Scott E. Lanis 80

Beating Reflections Check your sensitivity at half-scale or lower
But ensure that its high enough to receive adequate signal Reflections will generally be weaker than the most direct path to the target Following reflections will generally take your closer to the target If sensitivity is set to minimum, try DFing on a different frequency For example, if you are trying to locate an actual ELT on MHz, try locating it on or MHz when you get close When all else fails, fly somewhere else to get a good DF bearing-or try that at the first sign of problems! ©2000 Scott E. Lanis 81

Carrier-Only Signals You don’t always need to hear the ELT or EPIRB to find it A carrier-only signal may be broadcasting with no audible sweep This is especially true with low or old batteries, damaged ELTs, or spurious transmissions You can identify a carrier-only signal by DEFLECTION If it looks like you’re finding an ELT, even if you can’t hear it, you have good DEFLECTION Good needle deflection generally indicates a signal that is strong enough to DF ©2000 Scott E. Lanis 82

Carrier-Only Signals Compare your deflection to another frequency
If you are using MHz, try it on MHz If deflection is the same in both frequencies, you DON’T have a signal, just random noise (or your DF unit may be broken) If deflection is different, keep at it! You have a signal. If a signal is only received on 243 MHz, it may be a malfunctioning antenna (e.g., an FAA tower). If you DF to the location (particularly on or near an airport) and you keep ending up at an antenna, investigate. Find out who owns the antenna and its purpose. Inform the IC and let the controlling agency troubleshoot the problem. ©2000 Scott E. Lanis 83

Vertical Reflections & Signal Dropout
The transmission pattern (similar to the reception pattern of the DF antennas, only for transmission) of an ELT is not a perfect circle or sphere (especially in the profile view) It has lobes, or, stronger and weaker points This is accentuated when the ELT is transmitting from a location above the surrounding ground When you get a good DF heading and the signal fades or drops out completely you may just be outside of one of the signal lobes When you reacquire the signal, it should be stronger than when you lost it (if its not, you’re probably going in the wrong direction!) ©2000 Scott E. Lanis 84

Signal Dropout NO SIGNAL SIGNAL HEARD
If you encounter a signal dropout, continue to fly on your last good DF heading You should reacquire the signal in a few minutes Actual time will depend upon your distance to the target If you are unable to reacquire, return to where you last heard the signal and re-DF NO SIGNAL SIGNAL HEARD ©2000 Scott E. Lanis 85

Signal Strength The rate of change in signal strength increases as you get closer to the transmitter, and RECeive mode or the STRENGTH window measures signal strength This is due to Maxwell’s inverse square law: When you double the distance from an object, the energy it you receive from it is 1/4 of what you originally received, or the inverse square: 1/(22) = 1/4 After Scottish Physicist James Clerk Maxwell, This is an inverse exponential relationship You will therefore need to turn down the sensitivity to keep the unit at half scale in the RECeive mode or STRENGTH window much more often as you get close to the source of the signal This should let you know that you’re getting close ©2000 Scott E. Lanis 86

Signal Strength Rate of Change

Cone of Confusion Cone of Confusion Antennas receive best when the “pole” is perpendicular to the signal (a 30 dB loss for cross-polarized) When you approach the directly overhead position on an ELT, your DF will become unreliable It may swing left and right It may center regardless of your heading You should practice to see what this “station passage” reading looks like It is similar to crossing a VOR ©2000 Scott E. Lanis 88

Reception in the “Cone of Silence”
You may also get a significant drop in ELT signal since the antennas receive poorly directly off of their tips (a 90 dB loss) Although called a cone of silence, you will probably only see & hear a large decrease in signal instead of complete silence POOR antenna GOOD ©2000 Scott E. Lanis 89

Pinpointing the ELT If you get a station passage indication, make an approximate 180 degree turn and DF back to the target Repeat this process using different approach angles each time, remembering that your path may be curved due to wind (like uncorrected NDB holding) The point where station passage is received several times should be the location of the target 2 3 1 ©2000 Scott E. Lanis 90

Pinpointing the ELT After you think you have the target located
make a low pass over the suspected location and visually scan if signal strength decreases significantly or drops out, climb back and try again this is not the target: sometimes false targets will appear due to reflections or other interference If you hear the ELT at low altitude, you probably have the right place a low pass down a runway might be a good idea if you suspect a particular airport Discuss signal offset method as another way to pinpoint the signal. ©2000 Scott E. Lanis 91

QUESTIONS? NOTE: The newest CAP Direction Finder, the SAR-DF 517, is in very limited use and so is not covered here. Information on this unit can be found at

Becker SAR-DF 517 Completely different theory of operation from L-Tronics DF Pseudo Doppler Shift Beyond the scope of this course The advanced ELT course has an explanation Easy to use Displays a delayed average heading to the beacon Can be used on 121.5, 243.0, or MHz Able to process newest ELTs, EPIRBs, & PLBs

Becker Operation Power Mode Page Tune Squelch DF Locate

Power POWER Press the ON/OFF button—unit should power up and illuminate Be prepared to execute the next steps… If you’re not fast enough, you may need to recycle power (turn it off and back on)

Mode MODE Using the PAGE knob (upper right knob), select:
EMERGENCY for an actual SAR or TRAINING for a training mission This setting can only be changed on power up Recycle power to change the Mode After setting EMERGENCY or TRAINING, just WAIT until the unit automatically goes to the next page The “wait time” is about 15 seconds Don’t push any buttons or turn any knobs during this period

Page Use the PAGE knob to cycle to desired page
Page 1 is most like an ADF Page 2 is good for forward quarter only Page 3 is most easily read by the entire crew, but only in relative bearing

Tune The lower-right +/- knob changes the frequency
You want 121,500 for an actual SAR or 121,775 for training You can alternately use 243,000 or 243,550 respectively You will only be able to select training frequencies while in the training mode Similarly, you can only select actual SAR frequencies in the emergency mode 156,800 is for Marine Band Channel 16 EPIRBs Notice the commas: the Becker is made in Europe; the commas replace a decimal point

Squelch Setting Triangle
Adjust the squelch knob on the upper left of the unit The squelch knob may be marked SQL or DIM (depending when your Becker was made) Adjust the small triangle arrow until it is pointing barely above the solid bar The solid bar represents static or ambient noise, but you will want to listen and make sure that the “static” is not actually a signal When trying to acquire a signal, you may want the squelch all the way down You may also want to do this to make sure you can hear audio from the Becker Turn the lower left knob to adjust the volume to a comfortable listening level Squelch Knob Squelch Setting Triangle Ambient Noise Level

DF (Direction Find) Follow the relative bearings to the ELT
Use homing procedures like an ADF Correct for strong winds, if known Remember that these are RELATIVE bearings with the nose of the aircraft being 360°/ 000° !!! If you are showing a >006> that means turn right 6° If the unit shows <354<, then turn LEFT 6° This is similar to a fixed-card ADF “Rub The Tub” RB + TH = TB Relative Bearing + True Heading = True Bearing This is also true if we replace magnetic bearing and heading instead of the trues: RB + MH = MB Therefore if the Becker DF indicates >010> and you are flying a 270° heading, the magnetic bearing of the ELT is 280°. Add right, subtract left.

Becker Direction Finding Notes
The clear marbles indicate when the Becker first and last receives the ELT signal in its circle Watching the clear marbles will give you an indication of how coherent your DF solution is The marbles will always jump around; if they jump around a LOT you don’t have a good DF You can test this by seeing what your indications are when you reduce the squelch enough to “DF” static The clear marbles will jump all over the place Static can sometimes look like a carrier-only signal The dark marble should be fairly stable on an actual signal because of signal-averaging software >020> DARK MARBLE CLEAR MARBLES

Locate After flying over the ELT, you should get a “station passage” indication Turn around and re-DF to locate the target This is similar to locating with the L-Tronics DF If you keep the signal at 090 or 270, you can fly a “turn around a point” using the DF If the target isn’t visually significant, this will give your Scanner(s) the opportunity to put eyes on the target

Bearing on More than One Transmitter
If bearing from a long distance, the DF will be pointing at the middle of the two transmitters This is because the Becker averages the signals it gets Exactly in the middle between two transmitters, the DF will display an unusable bearing value The clear marbles will swing WIDE (180 degrees or more) when in the middle of 2 averaged signals Exactly over one transmitter the DF will be pointing to another (garbling cone) Tactic for this situation: don’t fly the approach exactly following the indicated averaged bearing: fly about 20 degrees left or right

Becker Thoughts The Becker unit is not as sensitive as the L-Tronics DF, so you must be significantly closer to the ELT to get initial signal Because it uses averaging functions, it will not instantaneously point to an ELT like the L-Tronics unit—there is defnitely a delayed raction The displays on the Becker lead you to believe that it is a pseudo-RMI or ADF type pointer. This is not the case. Even when the complete circle (page 1) is displayed, the arrow only indicates left or right, NOT how much (such as an ADF). The same is true for the “pie” display, page 2 Look to the “dark marble” to indicate the relative direction of the signal; this acts as an ADF-type pointer

Becker Thoughts Look to the “dark marble” to indicate the relative direction of the signal; this acts as an ADF-type pointer If you do not have an operable training beacon to practice with, pick an AWOS, ASOS, or other continuously-transmitting source that is within the training frequency range. If you tune it in (see the manual, training mode only) you can DF it. A caution with this method, however, is that an AWOS transmits at least 250 times the power level of an ELT. This makes DFing an AWOS much easier than an ELT Be careful with the unit as it costs roughly $10,000. MAKE SURE THE UNIT IS OFF DURING ENGINE START/SHUTDOWN. Some installations have the DF independent of the avionics master and the unit is sensitive to surges from start/shutdown. The complete user manual is available at

After Locating The ELT After location, coordinate with ground teams to bring them on-scene Use radio communication and relay GPS coordinates Pick up the ground team at a predetermined location and lead them to the target Alternately, coordinate a new pick up point on the radio Practice your air-to-ground coordination skills often try it both with and without radio communication Air-to-ground is CAP’s best unique ES skill! ©2000 Scott E. Lanis 106

DF upon Landing Many times the ELT is located at an airfield where it is easier for you to land and locate the ELT than it is to get a ground team to the scene You can use a hand-held radio or hand-held DF unit The most commonly used handheld DF in CAP is the Little L-Per You did remember to put one of these (with fresh batteries) in the aircraft before you left, didn’t you? Practice with the Ground/Urban DF teams.

Little L-Per Six Steps Receive Half DF Center Turn Shoot
The “Tracker” (made in Finland) is much easier to use and more accurate. More expensive, though. Advertises in CAP News.

OK, which of these planes is it in?
Use Little L-Per or… Use Body Shielding With any hand held aviation band radio, you can locate an ELT A Jetstream radio also works great Same concept as wing null method, you are just using your body to block the signal to the antenna When you get very close, there will be too much signal to get a null Use Frequency Offset Method—try instead of 121.5 As you home in, tune in 121.6—you can tune further away the closer you get

How To Body Shield: The Null
SIGNAL No Signal To Your Receiver The Sound Gets Softer! The ELT Is Directly To Your Back Throw your thumb over your shoulder to point to the ELT ELT

Airmobile UDF Team 101 Once you’ve narrowed the suspects down to one or two aircraft (usually side-by-side), remove the radio’s antenna and hold it next to one of the ELT antennas Turn the volume down until you just hear the signal Don’t key the radio’s transmitter with the antenna removed Move to the other aircraft’s ELT antenna If the signal is stronger you probably have it; if weaker, its probably the other aircraft May also put an aluminum foil ‘sleeve’ over the antenna Can also combine this with the frequency-offset method

OK, where is the thing? (IN the aircraft!)
ELTs are usually located in or near the rear of the aircraft. Also look for remote switches. Single-engine Cessna: right side of the upper baggage area immediately aft of the baggage door Multi-engine Cessna: left side of the fuselage just forward of the horizontal stabilizer. Accessed through a small push-plate on the side of the fuselage. Single- and multi-engine Piper: in the aft fuselage. Accessed through a small access plate on the right side of the fuselage. Single- and multi-engine Bonanza: in the aft fuselage. Accessed through a small access plate on the right side of the fuselage. Large piston twins (e.g., King Air) and small jets: if installed its probably in the rear section. No visible antenna. May have a small round push-plate that lets you manipulate the ELT switch. Keep a record for future use.

Silencing the ELT The preferred method is to have the owner (or someone designated by the owner) turn it off and disconnect the battery Second best is to just turn it off The owner may put the switch to ‘Off’ This may not always work since a malfunctioning switch could be the problem If this is done, listen to to ensure the beacon has been deactivated and that it doesn’t go off again Remind the owner he will need a new battery if the ELT has been transmitting for more than an hour A “foil tent” is seldom used–it is temporary and last resort 10.10 Objective 10.7 – Describe how to silence an ELT and the legal issues involved.

YOUR ELT/EPIRB HAS BEEN DEACTIVATED!
Silencing the ELT Ensure that the owner is notified that the ELT was disabled If you can’t get a phone number, you can place a note on the aircraft (not the window) ®® WARNING! ¬¬ to prevent interference with a bona fide emergency and with the Search and Rescue Satellite System, YOUR ELT/EPIRB HAS BEEN DEACTIVATED! by: C.A.P Search & Rescue Team For Further Information, Contact: name, phone # Can make your own.

Legal Issues Per CAP regulations and trespassing laws, CAP members will not enter private property and should not do anything that could cause harm or damage to the distress beacon or aircraft/vessel CAP members do not have the authority to trespass onto private property, either to gain access to the aircraft or to enter the aircraft to gain access to the ELT Entry to the ELT should be made by the owner or operator or law enforcement A transmitting ELT is under the legal authority of the FCC, and federal law requires that it be deactivated ASAP (a crashed aircraft is under the authority of the NTSB) Besides the owner/operator, some owners give FBO personnel permission to enter their aircraft Don’t let all this legal stuff intimidate you; its your job to find it and silence it.

Legal Issues While entry upon private property may be justified if such an act is for the purpose of saving life, every effort should be made to obtain the controlling agency's and/or the property owner's consent If you need entry onto private property in order to search for an ELT, law enforcement authorities such as local police, the county sheriff's office or game wardens may be contacted for assistance. Normally, local law enforcement officials are happy to assist you; if they are not familiar with CAP and your responsibilities, a simple explanation often suffices If this doesn't work, try having your IC calling AFRCC and have them explain the situation

Legal Issues The most important aspect is the manner in which you approach the matter The local civil authorities are in charge, if they tell you go home, then phone the IC and/or AFRCC and close the mission Friendliness, courtesy and respect go a long way.

QUESTIONS? Good Luck and Good Hunting!
Be sure to submit paperwork for “Find” and “Save” awards (CAPF 2a) for yourself and your crew. ©2000 Scott E. Lanis 118

Mission Aircrew Course Electronic Search Patterns (APR 2010)

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Mission Aircrew Course Electronic Search Patterns (APR 2010)

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